The present invention relates to a method of manufacturing a porous electroformed object, and more particularly to a method of manufacturing a porous electroformed object which will be used to form a covering layer that serves as an interior component of an automobile, for example, according to a vacuum forming process, by coating an organic solvent on an electrically conductive layer on a pattern model, adhering particles that can be dissolved by the organic solvent to the electrically conductive layer, depositing a metal layer on the electrically conductive layer in an electroforming process, and then dissolving away the particles for thereby producing an electroformed object which has a desired number of vent apertures of desired diameters that can easily be selected at desired locations.
Console boxes and other interior components of automobiles have covering layers with their outer surfaces having certain designed surface irregularities. The covering layers of these automobile interior components are usually in the form of sheets of synthetic resin such as polyvinyl chloride which are formed by the vacuum forming process using a porous electroformed mold having a plurality of vent apertures.
Porous electroformed objects for use as molds in the vacuum forming process have heretofore been manufactured according to various methods. In one method, an electrically conductive layer is formed on the surface of a model having a desired covering pattern, then an electroformed shell is produced of metal deposited on the conductive layer by an electroforming process, and thereafter the electroformed shell is separated from the conductive layer and drilled or processed by laser machining to produce a porous electroformed object.
The laser machining process requries a considerably expensive piece of equipment, and is time-consuming in the formation of a multiplicity of vent holes or apertures. Therefore, the laser machining process is poor in productivity. The drilling process is disadvantageous in that vent apertures of a diameter smaller than the diameter of the drill cannot be formed, and that many processing steps are required to form a number of vent apertures as with the laser machining process.
Japanese Laid-Open Patent Publication No. 60-152696 discloses a method of manufacturing a porous electroformed object by forming on the surface of a model a sprayed layer comprising an electrically conductive coated film mixed with an insulating material such as a lacquer solution of vinyl chloride, and electrolyzing the model in an electrolytic solution. According to this method, however, vent apertures cannot selectively be defined in the electroformed object at desired locations. Therefore, if the electroformed object has a complex shape, it is difficult to bring a synthetic resin sheet into intimate contact with the electroformed object in the vacuum forming process, with the result that a defective product may be fabricated. Another problem is that an electrolytic solution has to be prepared solely for use in this method.
Another known method disclosed in Japanese Laid-Open Patent Publication No. 61-253392 produces a porous electroformed object by forming a silver layer on the surface of a model through the silver mirror reaction, coating a silver etchant on an area of the silver layer where vent apertures are to be defined, and depositing a metal layer in the electroforming process. This disclosed method however requires an area of the silver layer where no vent apertures are needed, to be sealed, and should include a procedure for coating the silver etchant on the area where the vent apertures should be defined. As a result, the entire process of producing a porous electroformed object is complex, and the porous electroformed object cannot be fabricated efficiently. Since the silver etchant is employed, any particular locations where vent apertures are to be formed cannot specifically be identified, and it is impossible to select the diameter of such vent apertures as desired.
The applicant has proposed a method of manufacturing a porous electroformed object by first forming an electrically conductive layer on the surface of a model, putting a layer of particles on the surface of the conductive layer, depositing a metal layer through the electroforming process to produce an electroformed shell, and then dissolving away the particles to form a plurality of vent apertures in the electroformed shell (see U.S. Patent Ser. No. 813,252). The proposed method is advantageous in that an electroformed object having many minute vent holes can easily and efficiently be produced through quite a simple process.